Hi Jarkko,
On 6/9/23 10:24 PM, Jarkko Sakkinen wrote:
On Thu Jun 1, 2023 at 9:42 AM EEST, Tianjia Zhang wrote:
When integrity_inode_get() is querying and inserting the cache, there
is a conditional race in the concurrent environment.
The race condition is the result of not properly implementing
"double-checked locking". In this case, it first checks to see if the
iint cache record exists before taking the lock, but doesn't check
again after taking the integrity_iint_lock.
Fixes: bf2276d10ce5 ("ima: allocating iint improvements")
Signed-off-by: Tianjia Zhang <tianjia.zhang@xxxxxxxxxxxxxxxxx>
Cc: Dmitry Kasatkin <dmitry.kasatkin@xxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx> # v3.10+
s/v3.10/v4.14/
I.e. cover only currently maintained longterms, right?
Yes, the race condition was indeed introduced in 3.10, but the fix is
estimated to only cover the LTS version.
---
security/integrity/iint.c | 15 +++++++++------
1 file changed, 9 insertions(+), 6 deletions(-)
diff --git a/security/integrity/iint.c b/security/integrity/iint.c
index c73858e8c6d5..a462df827de2 100644
--- a/security/integrity/iint.c
+++ b/security/integrity/iint.c
@@ -43,12 +43,10 @@ static struct integrity_iint_cache *__integrity_iint_find(struct inode *inode)
else if (inode > iint->inode)
n = n->rb_right;
else
- break;
+ return iint;
}
- if (!n)
- return NULL;
- return iint;
+ return NULL;
}
/*
@@ -113,10 +111,15 @@ struct integrity_iint_cache *integrity_inode_get(struct inode *inode)
parent = *p;
test_iint = rb_entry(parent, struct integrity_iint_cache,
rb_node);
- if (inode < test_iint->inode)
+ if (inode < test_iint->inode) {
p = &(*p)->rb_left;
- else
+ } else if (inode > test_iint->inode) {
p = &(*p)->rb_right;
+ } else {
+ write_unlock(&integrity_iint_lock);
+ kmem_cache_free(iint_cache, iint);
+ return test_iint;
+ }
}
iint->inode = inode;
--
2.24.3 (Apple Git-128)
Mimi, are you picking this?
Mimi has picked this patch in next-integrity.
Off-topic: how do you compile kernel on macOS, you're using VM right?
I'm just interested because I recently bought Mac mini for both
compiling and testing arm64. Optimal would be to be able to compile
the kernel on bare metal and then deploy to a VM...
I am currently only coding and sending the final patch on a Mac.
Compilation and testing are still carried out in the linux environment.
If you have experience in launching a linux VM on macOS, please share it
with me, thanks.
Best regards,
Tianjia
